1. Field of the Invention
The present invention relates to methods of and apparatus for manufacturing stiffened structures made from composite materials such as carbon fibre composites.
2. Discussion of Prior Art
In many areas of manufacturing lightweight, strong, structures are made from composite materials which are easy to form into complex three dimensional shapes. Automobile bodies and aircraft structures such as wings and intake ducts are commonly made from these materials. Often such structures are large and require stiffeners to give them added strength and rigidity and sometimes to provide attachment points to other structures.
Conventionally stiffened composite structures are made by forming the basic structure from uncured composite material using a mould tool whilst constructing the composite stiffeners separately also from uncured composite material. The separate stiffeners and moulded structure are then autoclaved to cure them and a difficult process then follows whereby the stiffeners are attached to the moulded structure. Typically the moulded structure will be held on a jig and a complex scaffolding erected around it. Extensive drilling of the structure and the stiffeners is then required and the two parts brought together for bolt and/or pin attachment. Where precise positioning of the stiffeners on the structure is required, say because the stiffened structure is to interface with another structure, this can be a very difficult procedure indeed and it can be extremely difficult to achieve the accuracy of drilling and location required because of the intrinsically variable nature of the jigs and scaffolding used.